In conventional fiber cleavers, a first portion of a fiber is mechanically clamped by a first clamp and then a second portion of the fiber is mechanically clamped by a second clamp. Once both clamps are secured to the fiber, one clamp is selectively moved away (or translated) from the other clamp until a proper amount of tension is applied to the fiber, between the clamps.
Once the proper amount of tension is applied, a surface of the fiber is scored with, for example, an ultrasonic diamond blade. Given the tension, the scoring of the fiber surface causes a crack to propagate through the fiber—achieving a cleave of the fiber.
FIG. 1 is a high level view of a fiber cleaver, in accordance with the prior art. The cleaver is configured to cleave an optical fiber 1, at a stripped portion 2 of the fiber. The cleaver includes a fiber hold down member 3 that sits on a resting table 4. The hold down member 3 holds the un-stripped portion of the fiber.
The stripped portion of the fiber 2 is held by two clamps 5 and 6. A first portion of fiber 2 is positioned in a bottom portion 5b of clamp 5 and then a top portion 5a of clamp 5 is closed to secure the first portion of fiber 2. Fiber 2 is clamped in clamp 6 the same way. That is, a second portion of fiber 2 is positioned in a bottom portion 6b of clamp 6 and then a top portion 6a of clamp 6 is closed to secure the second portion of fiber 2. Clamp 5 can be translated away from clamp 6 to apply a controlled and accurate amount of tension to the fiber 2, between the clamps 5, 6.
Presuming the fiber is tensioned between the two clamps 5 and 6, the stripped portion of the fiber 2 between the clamps 5,6 can be cleaved. A slider 7 includes a hard, sharp blade (e.g., an ultrasonic vibrating diamond blade) that gets placed in contact the with the fiber 2 when the slider is moved in the direction of the fiber, within tracks 9. The blade 8 scores a surface of the fiber and the tension applied to the fiber causes a crack originating at the score to propagate through the fiber, resulting in a cleave.
In an ideal situation, the cleave is perfectly perpendicular to a central axis (and surface) of the fiber. However, the ideal is not practically achievable, largely because clamping with the second clamp causes a small, yet important, torsion to the fiber. The torsion causes the propagation of the crack to be slightly off perpendicular.
When the ends of two fibers being spliced together are not perfectly perpendicular with respect to their surfaces, the imperfect junction of the fibers adversely impacts the transmission properties of the spliced fiber.
The problem of torsion from the second clamp exists with fibers having a circular cross section. This problem is further exacerbated with fibers having other than circular cross sections and multi-strand or bundled fibers.